The process of this invention is used to prepare ethylene glycol and methanol. More particularly, the process prepares ethylene glycol and methanol in one step from carbon monoxide, hydrogen and formaldehyde under moderate reaction conditions using a catalyst comprising a rhodium compound.
Ethylene glycol is an important industrial alcohol known primarily for its use as an organic solvent and nonvolatile antifreeze or coolant. It is currently produced by a variety of methods. On a commercial scale most ethylene glycol is produced by hydrolysis of ethylene oxide with dilute sulfuric acid, or with water, at high temperature. EQU (CH.sub.2).sub.2 O + H.sub.2 O .sup.200.degree. C. HOCH.sub.2 CH.sub.2 OH
in yet another process ethylene glycol is produced by the high temperature, high pressure reaction of carbon monoxide and hydrogen. For example, German Pat. No. 2,426,495 describes a process for producing ethylene glycol and methanol by the metal-carbonyl-catalyzed reaction of hydrogen and carbon monoxide at high pressures and temperatures. ##STR1##
U.S. Pat. No. 2,451,333 granted Oct. 12, 1948 and German Pat. No. 875,802 illustrate the conventional two-step hydroformylation and reduction of formaldehyde. According to the disclosures, hydroformylation of formaldehyde using a cobalt catalyst yields a mixture of acetals and acetaldehyde, which can be reduced to ethylene glycol and ethylene glycol ethers. When the reaction is carried out in an alcohol solvent, the major product is the glycol ether.
The prior art has relied upon harsh reaction condition or multiple step processes to prepare ethylene glycol usually with the formation of by-products such as ethers. Accordingly, a one-step process which can be conducted under moderate conditions without excessive formation of by-products is desirable.